Preparation Process And Microstructure Analysis Of Ni Matrix Composites

Nickel base alloy has excellent corrosion resistance and heat resistance.in marine desalination,wastewater treatment,atomic power generation,refining,chemical and other fields it have excellent applications.But nickel base alloy has poor hardness and poor self-lubricating properties.This research fabricated the Ni-WC composite and Ni-MoS2 through powder metallurgy.The Rockwell hardness tester,optical microscope,X ray diffraction(XRD),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS)were used to study the effect of concentration of the composites,the sintering process of composites and the reinforcement of WC and MoS2 on the microstructure and properties of composites.Through the heat treatment process of Ni-WC Composites,the effects of solution time and aging time on the microstructure and properties of Ni-WC composites were studied,and the heat treatment process was optimized.Research results show that:1.Ni/WC composites and Ni/MoS2 Ni-based composites were fabricated by powder metallurgy technology.The densities of-the composites were higher and the particles were uniformly distributed in the Ni matrix.2.When the WC particles are added into the alloy,some of the WC is dissolved in ?-Ni and the other part of the WC particles is evenly distributed in the alloy.When cooled,a large amount of the second phase is precipitated in ?-Ni.Increase.When MoS2 is added to the alloy,the amount of(?-Ni + NiMo)eutectic structure increases with the increase of the content of MoS2,and the partial Cr dissolves in the NiMo intermetallic compound to form Ni(Mo,Cr)Leading to a decrease in the amount of M7C3 carbides in the alloy.The strengthening effect of the second phase is weakened and the hardness of the alloy is low.3.Based on the analysis of sintered samples,it is known that Ni60 alloy consists of ?-Ni dendrites,carbides,Ni3B particles and Ni-Ni3B eutectic structure.Ni-WC alloy mainly consists of ?-Ni,carbides,WC and Ni-Ni3B eutectic structure.When WC particles were added in Ni60,some WC dissolved in y-Ni,and the other WC particles were uniformly distributed in the alloy.When cooling,the second phase of?-Ni was precipitated.Ni-MoS2 alloy is mainly composed of ?-Ni dendrites,carbides and Ni-Ni3B eutectic structure,Ni-NiMo eutectic structure,and with the increase of MoS2 content in the alloy(?-Ni+NiMo)significantly increased the number of eutectic.4.Ni60/10%WC alloy after solution treatment is mainly composed of ?-Ni supersaturated solid solution,carbide M7C3 and WC.The alloy is mainly composed of y-Ni supersaturated solid solution and carbide M7C3.composition.When the aging treatment is carried out between 300? and 500?,the amount of precipitates in the alloy increases,the strengthening effect of the second phase is remarkable,and the hardness of the alloy increases.When the aging temperature is about 500?,The hardness of the alloy reaches the maximum value,and the aging temperature increases continuously.The second phase keeps growing and disperses,the diffusion degree decreases,and the second phase strengthening effect decreases.Therefore,when the aging temperature is 500 ? to 700 ?,the hardness of the alloy decreases gradually.